Not sure if my block heater is working

Question

Whenever I plug my car in, 2013 Nissan Maxima, I can always hear a fizzing sound at the beginning followed by a constant hissing. It sounds like it's working, however when I start the car in the morning, the temp gauge is still at its lowest point.

Same thing happened this morning. The car was left plugged in for around 6-7 hours, and the outside temperature was -8 C (17.6 F) at its lowest point.

This is the OEM block heater.

Answer 1

I am not familiar with Nissan's exact block heater, but am going to give you some general maintenance tips to help you attempt to resolve your issue.

1. First thing to do is to ensure the plug and cord and undamaged. These cords are exposed to the elements and often get damaged.
2. If the cord is ok. Check the prongs for corrosion and use a wire brush or Scotch brite pad to clean the prongs to ensure a good connection when it is plugged in.
3. Check the connection at the block. Some heaters are sealed, while others have a connection to make it easier to replace the cord. Look for corrosion and damage at that connection.
4. The next test you will need a multi-meter set to ohms. If the cord is in good order, connect one lead to each of the flat prongs on the plug. If the plug is damaged, you will want to make this connection as the heater itself. This will check resistance thru the heater. The resistance (ohms) should not be zero. Ideal resistance will be 20 to 30 ohms. IMO, anything below 10 ohms may be suspect.

Note: The resistance I am referring to is a 120 volt system. In some countries the electricity is 230 volts and the resistance will be in the 70 to 110 ohm range.

Obviously, a damaged cord will need to be replaced. If the block heater needs to be replaced, it will require draining some coolant from the engine, so be prepared to catch the fluid or have a garage perform the work for you.

Answer 2

I have used a relatively powerful electric heater for my 2016 Toyota RAV4 hybrid. I believe the power is 700 watts. It is not an old-style block heater but not one of those that you attach to the side of the engine either. It actually heats the coolant with a circulating pump.

Even if I use the coolant heater for 2 hours, when starting the engine, the temperature gauge is still in the lowest point. Basically, the temperature gauge of a car is not designed to say whether the coolant is 0 degrees Celsius or 20 degrees Celsius; it's designed to say whether the coolant is 80 degrees Celsius or 100 degrees Celsius.

So, don't worry about the temperature gauge being at the lowest point. Your block heater is most likely working properly nevertheless. Unless you have a far more powerful heater than I do (which is very unlikely, considering that your heater probably doesn't have a circulating pump), the temperature gauge is not supposed to display the effect of the heater.

If it's really cold outside (like -20 degrees Celsius), as you have a non-hybrid, you could always try to start the car with and without the block heater. On non-hybrid cars, starting at -20 degrees Celsius can take a second or so if you didn't use the block heater. The block heater should reduce the startup time considerably. So, you can see the effect from how easily the engine starts. Hybrid engines always start easily, so on my car I can't tell the difference.

You could always verify the operation of the heater by purchasing $10-$20 wattmeter and observing the used power. If the power is over 200 watts, your heater is probably operating normally. It is difficult to say what amount the wattmeter should show, as I don't know the specs of your block heater, but generally heaters are between 200W and 1000W, and the highest part of the range requires circulating pump for the coolant.

If you want the interior of the car to be warm, I recommend purchasing an interior heater. They are generally far more powerful than block heaters (mine is 1900W, I believe).